Qualities of a Good Index

Posted on: 20/10/2023

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Creative Commons licence BY 2.0 Image by Alex Proimos from Sydney, Australia, , via Wikimedia Commons

In this blog post, Lyndsay Marshall looks at the qualities of a good index and identifies resources which discuss the topic in more depth. The post covers international standards, best practice guidelines and competition judging criteria.

International Standards

In order to define the qualities of a good index we can turn to the international standards of indexing:

  • ISO 999:1996 Information and documentation – Guidelines for the content, organization and presentation of indexes (this international standard is adopted in the UK as BS ISO 999).
  • ANSI/NISO Z39.4-2021 Criteria for Indexes (American National Standards Institute/National Information Standards Organization).

The Society of Indexers has created a list of the key differences between the two standards, which is available to SI members via the website.

Nancy Mulvany discusses what constitutes the “ideal index” (Indexing Books, 2005 p17). She recommends turning to the “Function of an Index” section in ISO 999 as a starting place. Paragraph 4 states, “the function of an index is to provide the user with an efficient means of tracing information,” (ISO 999, p3) followed by a list of 10 subpoints covering appropriateness of terminology, efficiency of information retrieval, conceptual relationships, grouping of scattered mentions and exclusion of passing mentions.

Best Practice Guidelines

The American Society for Indexing has published a guide to indexing best practice. Paragraph 11 lists the characteristics of a quality index including: accuracy of terminology and page locators, clarity of terminology and in the relationships between concepts, conciseness, consistency of format, the use of everyday language, comprehensiveness, accessibility from a range of entry points, neutrality (avoidance of bias), and readability. A shorter guide is provided by the Institute of Certified Indexers.

Pat Booth writes about “The Good Index”(Indexing: The Manual of Good Practice, 2001, pp14-16). She refers to the intellectual and presentational features of an index. The intellectual features include coverage of key topics using concise, meaningful headings which cover significant information with accurate page locators. The presentational features include alphabetical (or other) order, consistent layout of headings, locators, punctuation and style.

Competition Judging Criteria

Indexing competitions have sought out excellence in indexing but two of these have been retired in recent years; the ASI Excellence In Indexing Award (retired in 2021) and the Society of Indexers’ Wheatley Medal (retired in 2012). However, we can look back at the judging criteria of these competitions as indicators of what constitutes excellence in indexing. A short checklist for the Wheatley Medal was provided in an article by David Lee from 2001 (p194). The six key points were accuracy, consistency of coverage, clarity (including introductory note), avoidance of undifferentiated locator strings, presentation, and handling of subject content. The ASI criteria has four key sections: structure, mechanics (accuracy, cross-references, style, layout etc), substance (analysis, coverage, terminology, usability), and elegance (clarity, consistency, readability, completeness).  A full list of previous winners of the Wheatley Medal is available and these can be sought out as examples of excellence.

In summary, we can see that a “good index” is one which meets its main purpose, as an efficient means of finding information. The fine detail of how this is achieved is found in the best practice guidelines and international standards. These include intellectual features (subject analysis, term selection, appropriate use of terminology, use of subheadings, cross-references) as well as presentational features (ordering, use of formatting for differentiation of types of information, layout).


These are the resources and links mentioned above. Follow the links to find out more:


ISO 999:1996 Information and documentation – Guidelines for the content, organization and presentation of indexes.

ANSI/NISO Z39.4-2021 Criteria for Indexes.


Society of Indexers, Wheatley Medal

American Society for Indexing Indexing Award

Best Practice Guidelines

American Society for Indexing – Best Practices for Indexing

Institute of Certified Indexers – Indexing Best Practices

Books and Journal Articles

Booth, Pat. Indexing: The Manual of Good Practice (K. G. Saur, 2001).

Hamilton, Geoffrey. How to recognise a good index. The Indexer, 1976, 10(2) 49-53.

Lee, David. Judging indexes: The criteria for a good index. The Indexer, 2001, 22(4) 191-4.

Mulvaney, Nancy C. Indexing Books (University of Chicago Press, 2005).

Uschtrin, Sandra and Fassbender, Jochen. The Art of Indexing. The Indexer 2001, 29(1), 13-18.

About Lyndsay Marshall

Lyndsay Marshall indexes academic books in literary studies, cultural studies, theology, religious studies, and the social sciences, producing standard and embedded indexes. She is a BSI committee member, representing SI on the Identifiers and Metadata committee. She is also Minutes Secretary to the Executive Board.

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